The present invention is directed to a wired, alarm control-panel system for protecting a premises site, such that upon the system's sensing an alarm condition, connection between the premises-wiring and the public switched telephone network, or PSTN, is broken or terminated, and which connection to the PSTN is thereby seized by the alarm control-panel system in order to transmit to, and receive alarm data from, an alarm central station, or the like, over the PSTN. When this alarm condition occurs, any telephone device attached to the premises-wiring is rendered inoperable for the period that the alarm-panel's PSTN-seizure is in effect. Such seizure of the PSTN and the isolation of the premises-wiring is a considerable problem, especially in time of an emergency. The occupant of the premises, or client, does not know if the disconnected line is due to an alarm seizure by the alarm control-panel system, or due to a break in the connection to the PSTN that was caused by the emergency. In addition, the client does not know when the premises-wiring has been reconnected to the PSTN, so that a telephone call may then be made.
Examples of conventional alarm control-panel systems that seize control of the PSTN during an alarm condition for reporting the alarm condition to a central monitoring station, or the like, which seizure also cuts off the premises-wiring from connection to the PSTN is shown in U.S. Pat. No. 4,718,079—Rabito, and U.S. Pat. No. 5,131,019—Sheffer, et al.
It would be highly advantageous to provide an alarm control-panel system that monitors a premises for alarm conditions which will notify, warn, or otherwise indicate to the occupant or client of the protected premises when the alarm panel of the alarm control-panel system has seized control of the PSTN-connection, and, also, when the alarm panel has relinquished seizure thereof. This would permit a more reliable use of the premises' telephone devices to make and receive calls, especially in emergency conditions.